Analysis of defects in stainless steel piping

This article presents the evaluation of defects detected in the austenitic stainless steel piping in the main circulation circuit of Ignalina NPP Uunit 2 during the last planned preventive maintenance in 2008. Defect evaluation procedure consists of two parts: the evaluation of defects acceptability and the second part consists of crack growth calculation. For the evaluation of defects R6 option 1 method was used. The analysis showed that all 126 detected defects during planned preventive maintenance in 2008 are in acceptable region and all the welds can be used without repairing. These piping will be used even at NPP decommission stage during decontamination procedure. Therefore the impermeability of piping should be ensured for decommissioned NPP until decontamination of the piping will be done. Evaluation of the defects in austenitic stainless steel piping should be done according to the methodology described in this article.