PSI - Issue 68

Tamás Fekete et al. / Procedia Structural Integrity 68 (2025) 915–921 T. Fekete / Structural Integrity Procedia 00 (2025) 000–000

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individual in advanced industrial societies has been made possible by the achievements of people engaged in the development of human culture over long millennia – Simonyi (2012 1–580.). Humans’ desire to reduce the physical effort involved in their work, to increase the efficiency and productivity of their work and to make their living conditions more comfortable has accompanied them throughout history and is still one of the main driving forces behind technical and economic progress. The efficiency of human labor increased rapidly in the 19 th century, when the steady Watt steam engine was able to extract mechanical power from the heat released by various primary energy sources, a power that had been beyond the reach of man in previous ages. Parallel to the wide use of steam engines, during the middle third of the 19 th century, electrodynamics, which can describe the electromagnetic properties of macroscopic matter, was created and its basic relationships –known as Maxwell's equations– were developed by J.C. Maxwell (1865). By the end of the 19 th century, the technical foundations for today’s AC power generation and distribution systems had been developed (K. Zipernowsky, M. Déry, O. Bláthy, N. Tesla, G. Westinghouse, etc.) and the first industrial-scale versions had been built. Industrial scale AC power generation began at the beginning of the 20 th century and is now an indispensable pillar of the energy supply in modern industrial societies. In the first half of the 20 th century, electricity was used primarily for lighting, powering telecommunications systems, and meeting the power needs of industrial motors, including trams and rail traction. Since the mid-20 th century, electrically powered devices and machines have rapidly expanded into areas unimagined by previous generations. Perhaps the technological achievement that has had the greatest impact on the lifestyles and opportunities of ordinary individuals is the creation of the Digital Computer ( DC ), whose progressively miniaturized, increasingly complex and mass-produced versions, capable of ever greater computational power and cheaply manufactured, have fundamentally changed the way people in advanced technological civilization can access knowledge, technology, information and communicate with each other. The theoretical foundations of DC s were largely developed by J. von Neumann (1993). The programmable DC s on which today’s IT is based are still built on ‘von Neumann’ principles. The miniaturization of DC s has been achieved by the microelectronics industry, based on the findings of Quantum Mechanics and Semiconductor Physics – see e.g. Böer, Pohl (2023). Control theory – see e.g. Bechhoefer (2021), based on Cybernetics, developed by Wiener (1948) and implemented on DC s, paved the way for the development of a complex, intelligently controllable Cyber-Physical System for many machines that were previously only suitable for elementary functions. Industry 4.0, launched about 10 years ago, is also based on the concept of Cyber-Physical Systems – see Jasperneite (2012). In factories built according to Industry 4.0, previously physically demanding work phases are now performed by intelligent machines. These and other technological advances, too numerous to list here, have made the daily lives of ordinary people in industrialized societies much more comfortable, but this comfort can only be maintained if the electrical energy needed to run these comfort systems is generated by the appropriate power plant systems. Efficient and environmentally friendly power generation is one of the most important issues of our time, as the world’s demand for electricity is expected to grow significantly in both the short and long term. Nuclear Power Plants ( NPP s) are of particular importance to the electricity industry, both because of the stability of supply and because of their low environmental impact. A major issue today is the extension of the lifetime of NPP units into the Long-Term Operation ( LTO , i.e. ≈ 70-80 years of operation) range – see Katona, Biró, Rátkai (2023). Moreover, LTO also represents a challenge for R & D , since the technically allowable operating life of the units has to be predicted for the highly aged states of the structural materials of the safety-critical Large-Scale Pressure System ( LSPS ), for which there is relatively scarce scientific knowledge and no industrial experience. Even though the classic methodology of Structural Integrity Computations ( SIC s) used up to now has led to satisfactory results in previous projects, the need has arisen to rethink the methodology of SIC s from the outset in the light of the latest scientific developments. Generalized methodology of SIC s is based on a novel umbrella theory, which in the literature is called ‘Non-Linear Field Theory of Fracture Mechanics’ ( NLFTFM ) – Chen, Mai (2013). The underlying concept of the NLFTFM extends far beyond the concept behind the theoretical apparatus of the classic methodology of SIC s and is mostly known only to a limited group of specialists. Therefore, it seems worthwhile to present the essence of the new concept to the interested readership, as well as the considerations that justify the necessity of the Conceptual Shift from the old to the new concept and the methodological correctness of this Conceptual Shift. Due to space limitations, this paper summarizes the essence of the concept underlying the new methodology and its justification.