Abstract
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.
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References
Secretariat of Energy (2013) National report that presents Mexico to meet the requirements of the convention on nuclear safety. International Atomic Energy Agency (IAEA), Period 2010–2012
Ruiz P (2014) Structural integrity of the BWR jet pumps under the presence of relevant defects. Thesis to obtain the Degree of Master in Sciences, National Polytechnic Institute, Mexico
United States Nuclear Regulatory Commission, NUREG-1544 (1996) Status report: Intergranular stress corrosion cracking of BWR core shrouds and other internal components
United States Nuclear Regulatory Commission (1994) Intergranular stress corrosion cracking of core shrouds in boiling water reactors (Generic Letter 94-03), Office of Nuclear Reactor Regulation
Serrano M, Hernández M (2007) Programas de investigación sobre fragilización por irradiación de los aceros de la vasija. Anales de Mecánica y Electricidad, España
Gary S (2007) Fundamentals of radiation materials science, metals and alloys. Springer, Berlin
United States Nuclear Regulatory Commission, NUREG/CR-6826 (2003) Fracture toughness of irradiated stainless steel
United States Nuclear Regulatory Commission, NUREG/CR-7027 (2010) Degradation of LWR core internal materials due to neutron irradiation
Hernández LH, Urriolagoitia GM, Urriolagoitia G et al (2009) Assessment of the structural integrity of cracked cylindrical geometries applying the EVTUBAG program. Rev Téc Ing Univ Zulia 32:190–199
Zahoor A (1999) Ductile fracture handbook. Electric Power Research Institute Report NP-6301
Rahman S, Wilkowski G (1998) Net-section-collapse analysis of circumferentially cracked cylinders—Part I & II. Engineering fracture mechanics 61, Pergamon
Rao KR, Hardayal S (2009) Companion guide to the asme boiler and pressure vessel code, vol. 3. Chapter 41:bwr reactor internals and other BWR issues
http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=000000000001018251 (Internet consult made in June 20, 2015)
BWR Vessel and Internals Project, BWR Core Shroud Inspection and Flaw (2000) Evaluation guidelines (BWRVIP-76NP), TR-1 14232NP, Final report, Non-proprietary information, Appendix K guidelines for inspection of BWR core shrouds: demonstration of compliance with the technical information requirements of the license renewal rule (10 CFR 54.21), Electric Power Research Institute
Warren C et al (2002) Formulas for stress and strain. 7th edn. McGraw-Hill
Wong M (2009) Plastic analysis and design of steel structures. Elsevier
The American Society of Mechanical Engineers (2007) Section III rules for construction of nuclear facility components, Division 1—Subsection NB class 1 components, ASME boiler & pressure vessel code, 2007 edn
Acknowledgments
The authors kindly acknowledge the support given by CONACyT through the Project No. 211704, the National Polytechnic Institute and the National Commission on Nuclear Safety and Safeguards (Mexican Nuclear Regulatory Body) from Mexico.
Statement
The conclusions and opinions stated in this paper do not represent the position of the National Commission on Nuclear Safety and Safeguards, where the authors P. Ruiz-López and M.L. Serrano-Ramírez are working as employees. Although special care has been taken to maintain the accuracy of the information and results, all the authors do not assume any responsibility on the consequences of its use. The use of particular mentions of countries, territories, companies, associations, products or methodologies does not imply any judgment or promotion by all the authors.
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Ruiz-López, P. et al. (2017). Structural Integrity Analysis of a BWR Core Shroud with an Irregular Distribution of Cracks: Limit Load Analysis. In: Öchsner, A., Altenbach, H. (eds) Properties and Characterization of Modern Materials . Advanced Structured Materials, vol 33. Springer, Singapore. https://doi.org/10.1007/978-981-10-1602-8_32
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DOI: https://doi.org/10.1007/978-981-10-1602-8_32
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