A SENSIBILITY ANALYSIS IN THE STRUCTURAL RELIABILITY OF STEAM GENERATOR TUBES

Abstract

The present work performs a sensibility analysis of basic variables involved in thefunctional relation that describes the structural integrity of steam generator tubes. These basic variables are associated with geometrics, loading, and material properties, and are subjected to fluctuation of random nature. In a complex structural system, it is important to determine the impact of each basic variable on the failure probability, because this information may reduce significantly the statistical effort for asssessing the structural reliability. In this work, the structural reliability of steam generator tubes is assessed in terms of the failure probability by applying the FORM method. This method allows to easily perform a sensibility analysis concerning the importance factor. This sensibility measure is determined considering two failure acceptance criteria: the limit load and the FAD, and distinct tube materials: stainless steel 316, inconel 600, inconel 690 and incoloy 800. The results show that the yield stress is statisticaly more sensible in the FAD criterion than in the limit load. The fracture toughness has high importance factor for the stainless steel 316 in the FAD criterion.