Issue 36

T. Fekete, Frattura ed Integrità Strutturale, 36 (2016) 78-98; DOI: 10.3221/IGF-ESIS.36.09 78 Focused on Fracture Mechanics in Central and East Europe Methodological developments in the field of structural integrity analyses of large scale reactor pressure vessels in Hungary Tamás Fekete HAS Centre for Energy Research, Department of Fuel and Reactor Materials, Structural Integrity Group tamas.fekete@energia.mta.hu A BSTRACT . Buildings, structures and systems of large scale and high value (e.g. conventional and nuclear power plants, etc.) are designed for a certain, limited service lifetime. If the standards and guidelines of the time are taken into account during the design process, the resulting structures will operate safely in most cases. However, in the course of technical history there were examples of unusual, catastrophic failures of structures, even resulting in human casualties. Although the concept of Structural Integrity first appeared in industrial applications only two-three decades ago, its pertinence has been growing higher ever since. Four nuclear power generation units have been constructed in Hungary, more than 30 years ago. In every unit, VVER-440 V213 type light-water cooled, light-water moderated, pressurized water reactors are in operation. Since the mid-1980s, Pressurized Thermal Shock (PTS) analyses of Reactor Pressure Vessels (RPV) have been conducted in Hungary, where the concept of structural integrity was the basis of research and development. In the first part of the paper, a short historic overview is given, where the origins of the Structural Integrity concept are presented, and the beginnings of Structural Integrity in Hungary are summarized. In the second part, a new conceptual model of Structural Integrity is introduced. In the third part, a brief description of the VVER-440 V213 type RPV and its surrounding primary system is presented. In the fourth part, a conceptual model developed for PTS Structural Integrity Analyses is explained. K EYWORDS . Structural Integrity; Structural Integrity Analyses; Reactor Pressure Vessels; Pressurized Thermal Shock; Methodology. I NTRODUCTION uildings, structures and systems of large scale and high value (eg. conventional and nuclear power plants, chemical plants, gas and oil processing plants, long-distance energy transfer pipelines, bridges, airplanes, ships, etc.) are designed for a certain, limited (generally 15-30-50 years) service lifetime, taking the standards and guidelines of the era into account. These standards (eg. the ASME Code [2], the KTA Standards [49], and the VDI Standards [102]) and guide-lines (eg. PNAE [83], VERLIFE [104]) reflect the scientific and technological level of the previous years or decades. If they are taken into account during the design process, the resulting structures will operate safely in most cases. However, in the course of technical history there were examples of unusual, catastrophic failures of structures, even resulting in human casualties, e. g. the sinking of the Titanic, then the serial accidents of the Liberty-type ships, all of which happened in cold maritime conditions. In Hungary, there happened a catastrophic accident of a Carbonic acid B