Preliminary study of the effects of ageing on the long-term performance of NPP pipe

Cancemi, Salvatore Angelo; Frano, Rosa Lo

doi:10.1016/j.pnucene.2020.103573

Cited by 6 publications

(11 citation statements)

References 15 publications

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“…According to the study [ 8 ], five different cases have been considered: Case 1: item not affected by creep, thinning, and aging phenomena. This is the reference case.…”

Section: Analysis Resultsmentioning

confidence: 99%

“…Compared to study [ 8 ], in which the aging and thinning effects are analyzed for a simple straight pipe, the behavior of an elbow pipe along its longitudinal direction is the subject of this study (complex geometry).…”

Section: Methodsmentioning

confidence: 99%

“…In the numerical assessment, we assumed thinning rates (W r ) of the elbow equal to 0.5 mm/yr and 0.7 mm/yr, and 20% reduction of the nominal material properties [ 8 , 25 ]. Concerning corrosion/erosion phenomena, the thinning rate was determined based on the lesson learned from the Davis Besse NPP (Oak Harbor, OH, USA), the Japanese Mihama Unit 3 NPP accident [ 26 ], the study performed by Oh et al [ 27 ], and the database [ 25 ].…”

Section: Methodsmentioning

confidence: 99%

“…With reference to the study [ 8 ], an inner pressure of 14 MPa and a constant temperature of 300 °C are set-up for the entire transient period of 700 h. Material properties of the numerical model are assumed to be temperature dependent, in accordance with Table 2 , particularly those at 300 °C. The 304L properties are extracted from a materials database available in [ 25 ], collecting over 450,000 metal, polymer, ceramic, and composite material properties experimentally obtained in compliance with international regulations (e.g., ASME, ASTM).…”

Section: Methodsmentioning

confidence: 99%

“…Aging must be handled in order to ensure that especially the safety-related SSCs continue to guarantee their normal operation while being exposed to “damaging” conditions such as temperature, load, and environment to which the materials are exposed. This means that the safety level of each plant component and structure must always be maintained higher than its reference level [ 7 , 8 ]. Periodic inspections of the SSCs revealed unforeseen forms of degradation.…”

Section: Introductionmentioning

confidence: 99%

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Preliminary Analysis of Long-Term Performance of a Piping: Aging and Creep Effects

Cancemi

Frano

2021

Materials

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Combining global experience, comprehensive aging knowledge, and predictive methodologies provides ideal prerequisites for the long-term operation strategy (LTO) of a nuclear power plant (NPP). Applying management strategies with an understanding of the ways in which structures relevant for the plant safety perform and interact in their operating environments is of meaningful importance for operating the plant beyond its originally licensed service life. In performing aging studies on the nuclear systems, structure, and components (SSCs), the results are crucial for demonstrating the safety and reliability of the NPP beyond 30 years of nominal operation. In this study, the synergistic effect of a creep mechanism with the alteration suffered by piping material is analyzed by means of MSC©MARC finite element code. Nonlinear analyses were performed to calculate the effects of the long operational period on a primary pipe, assess its degradation, and determine its residual functionality. In these analyses, both homogeneous and inhomogeneous pipe wall thinning are considered, as well as the operating or expected thermal–mechanical loads. The obtained results indicate that thermo–mechanical loads are responsible for pipe deformation, which develops and increases as the transient progresses. Furthermore, an excessive (general or local) wall thinning may determine a dimensional change of the pipe, even causing bending or buckling.

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“…According to the study [ 8 ], five different cases have been considered: Case 1: item not affected by creep, thinning, and aging phenomena. This is the reference case.…”

Section: Analysis Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%