Abstract

The current requirements in ASME Section XI, 2021 Edition, Nonmandatory Appendix L provide guidance for evaluation of components when fatigue usage limits have been exceeded or fatigue usage is predicted to be of concern. As plants apply for subsequent license renewal (SLR), and in turn, fatigue accumulates on components within the reactor coolant system (RCS), flaw tolerance evaluations based on the guidance in Section XI Appendix L become increasingly necessary to assess fatigue. Through these evaluations and recent discussion during the ASME Section XI Task Group on Appendix L at the ASME Code Meetings, the following improvements to Section XI Appendix L are suggested: 1) add a tiered evaluation process for circumferential flaw shapes by first postulating a 360 degree flaw length and determining acceptability for piping components, before needing to move into the Equivalent Single Crack (ESC) aspect ratio tables that are already provided in Section XI Appendix L, and 2) clarify axial flaw procedures for postulated flaw shape in longitudinal welded seam ferritic pipes and austenitic pipes, as well as axial flaws postulated in seamless ferritic pipes and austenitic pipes (i.e., circumferential welds). This paper provides perspective of the impact of the suggested improvements to ASME Code Section XI Nonmandatory Appendix L flaw tolerance approach.

This content is only available via PDF.
You do not currently have access to this content.