{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T08:48:02Z","timestamp":1782809282280,"version":"3.54.5"},"reference-count":0,"publisher":"ECMS","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,6,23]]},"abstract":"<jats:p>The thin\u2011walled heat exchange tubes operating at high temperature and pressure also occur in the steam generators of pressurized water reactors. These components ensure the hermetic separation of the primary and secondary circuits, cool the reactor core, and produce the steam required for power generation.\n\nIn operating plants\u2014and likewise in Gen III+, Gen IV, and SMR designs currently under construction\u2014there are typically 1\u20134 steam generators, each of which may contain tens of thousands of such tubes. Because these tubes will be under high loads over the service lives, various tube failure modes must be anticipated, as decades of operation experience have shown. The isolation of defective tubes from service to preserve circuit hermeticity can reduce the heat\u2011transfer capability on the primary side and the energy available for steam generation; in critical cases, this process may even necessitate steam\u2011generator replacement.\n\nWe aim to develop the groundwork\u2014through numerical simulations\u2014for an evaluation method that meets FFS requirements, which can assess the combined effects of volumetric (pitting) and planar (crack) defects that form and act on the outer or inner tube surfaces. The procedure is designed to jointly assess the structural\u2011integrity impact of combined volumetric and planar flaws on the basis of non\u2011destructive examination (NDE) data, and to reliably forecast when these degradation mechanisms become critical, thereby supporting FFS\u2011based decision\u2011making.\n\nAs part of this foundation, we investigated equivalent crack geometries suitable for representing the effects of volumetric and planar defects. While different forms of FFS evaluations are widely used in industry, reducing combined failure mechanisms to a 2D formulation enables the criticality of these degradation modes to be checked against established assessment methods.\n\nTo achieve this, we applied four industry\u2011used approaches. First, we examined the combined depth of the volumetric and planar defects and approximated their effect with a semi\u2011elliptical surface crack. Secondly, we compared the difference in stress intensity factors (SIFs) using a semi\u2011ellipse equivalent to the projected area of the volumetric defect. Third, we compared the stress concentration factor (SCF) of a corrosion pit and a stress\u2011corrosion\u2011cracking flaw with that of a semi\u2011elliptical surface crack producing the same SCF. Fourth and finally, we determined a semi\u2011elliptical crack by fitting to the SIF values computed from the actual geometry of the combined volumetric and planar defect. The structural\u2011integrity effect of the resulting equivalent cracks are then evaluated by burst\u2011pressure analyses and crack\u2011growth simulations in a simplified FEM, in ANSYS environment.<\/jats:p>","DOI":"10.7148\/2026-0249","type":"proceedings-article","created":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T08:36:46Z","timestamp":1782808606000},"page":"249-255","source":"Crossref","is-referenced-by-count":0,"title":["Assessing combined degradation mechanisms in heat exchange tubes"],"prefix":"10.7148","author":[{"given":"Ferenc Aron","family":"Kaso","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter Tamas","family":"Zwierczyk","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4144","published-online":{"date-parts":[[2026,6,23]]},"event":{"name":"40th ECMS International Conference on Modelling and Simulation"},"container-title":["ECMS 2026 Proceedings edited by Filippo Sanfilippo, Florenc Demrozi, Fabio Sgarbossa, Mohammad Poursina"],"original-title":[],"deposited":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T08:36:54Z","timestamp":1782808614000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.scs-europe.net\/dlib\/2026\/ecms2026acceptedpapers\/0249_fdem_ecms2026_0128.pdf"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,6,23]]},"references-count":0,"URL":"https:\/\/doi.org\/10.7148\/2026-0249","relation":{},"subject":[],"published":{"date-parts":[[2026,6,23]]}}}