TY - GEN
T1 - Structural integrity analysis of a BWR core shroud with an irregular distribution of cracks
T2 - 9th International Conference on Advanced Computational Engineering and Experimenting, ACE-X 2015
AU - Ruiz-López, Pablo
AU - Hernández-Gómez, Luis H.
AU - Urriolagoitia-Calderón, Guillermo
AU - Serrano-Ramírez, María L.
AU - Ocampo-Ramirez, Arturo
AU - Beltrán-Fernández, Juan A.
AU - Urriolagoitia-Sosa, Guillermo
N1 - Publisher Copyright:
© Springer Science+Business Media Singapore 2017.
PY - 2017
Y1 - 2017
N2 - Mexico has a nuclear power plant with two BWR reactors. Their internal components were manufactured with type 304 stainless steel. Since the initiation of their commercial operation, some relevant cracks have been detected through the periodic inspections of their internals components. Specifically, there have been crack found at the core shroud and jet pumps. The causes of such cracks have been: excessive vibration, wear, stress corrosion cracking and residual stresses, acting alone or simultaneously. There are several aspects that have to be considered in the evaluation of the structural integrity of the core shroud, for instance: its shape is a cylinder and its R/t ratio is in the range between 60 and 100, as well as the water environment and the neutron irradiation. The last one has modified the mechanical properties of the material. Besides, each circumferential weld has a different non-symmetrical and irregular distribution of cracks with various depths. These cracks are monitored every 18 months, only during the plant shutdowns. Furthermore, the potential unstable cracking of the lower circumferential welds could induce important safety consequences if a loss of coolant accident and an earthquake event are postulated. Due to these reasons, it is very important to apply or develop adequate analytical procedures that can provide fast and reliable results. These procedures must cover elastic-plastic fracture analysis and plastic limit load analysis. In this paper, a methodology for the plastic limit load analysis was developed. The critical limit load for any crack distribution was calculated with a great degree of confidence. Operating conditions were considered. The shape of the cracks varies and the evaluation depends on the geometry of the cracked cylinder. In the problem at hand, the neutral axis varies, as it translates and rotates simultaneously at every cracked cross section, depending on the loading condition. This situation was also taken into account.
AB - Mexico has a nuclear power plant with two BWR reactors. Their internal components were manufactured with type 304 stainless steel. Since the initiation of their commercial operation, some relevant cracks have been detected through the periodic inspections of their internals components. Specifically, there have been crack found at the core shroud and jet pumps. The causes of such cracks have been: excessive vibration, wear, stress corrosion cracking and residual stresses, acting alone or simultaneously. There are several aspects that have to be considered in the evaluation of the structural integrity of the core shroud, for instance: its shape is a cylinder and its R/t ratio is in the range between 60 and 100, as well as the water environment and the neutron irradiation. The last one has modified the mechanical properties of the material. Besides, each circumferential weld has a different non-symmetrical and irregular distribution of cracks with various depths. These cracks are monitored every 18 months, only during the plant shutdowns. Furthermore, the potential unstable cracking of the lower circumferential welds could induce important safety consequences if a loss of coolant accident and an earthquake event are postulated. Due to these reasons, it is very important to apply or develop adequate analytical procedures that can provide fast and reliable results. These procedures must cover elastic-plastic fracture analysis and plastic limit load analysis. In this paper, a methodology for the plastic limit load analysis was developed. The critical limit load for any crack distribution was calculated with a great degree of confidence. Operating conditions were considered. The shape of the cracks varies and the evaluation depends on the geometry of the cracked cylinder. In the problem at hand, the neutral axis varies, as it translates and rotates simultaneously at every cracked cross section, depending on the loading condition. This situation was also taken into account.
KW - Aging
KW - License renewal
KW - Part through-wall thickness crack
KW - Plastic hinge
KW - Through-wall thickness crack
UR - http://www.scopus.com/inward/record.url?scp=84982949443&partnerID=8YFLogxK
U2 - 10.1007/978-981-10-1602-8_32
DO - 10.1007/978-981-10-1602-8_32
M3 - Contribución a la conferencia
SN - 9789811016011
T3 - Advanced Structured Materials
SP - 413
EP - 427
BT - Properties and Characterization of Modern Materials
A2 - Öchsner, Andreas
A2 - Altenbach, Holm
PB - Springer Verlag
Y2 - 29 June 2015 through 2 July 2015
ER -