Experience gained with inspection of metal state in thermal and mechanical equipment for extending operation time of power units of the first generation NPPs

The report is devoted to the topical problem of the present time - the extension of service life of the first generation power units. Solving of this problem is impossible without an estimation of technical conditions of the equipment and pipelines. In this way the survey of metal conditions is the primary importance. Taking into account a fact, that work regarding the service life extension of power units was carried out for the first time, it has required not only the elaboration of the methodology of the assessment of technical conditions and residual life, but also the elaboration of new methods intended for metal conditions inspection and its practical application on-site. At the same time an important moment was the necessity of development of the normative document base providing both technical and law support of the defined problem. This report considers the methodology, the newly developed methods and tools for metal inspection and the standard ones which being applied. Also the definite results of VNIIAES activities regarding the technical survey of the equipment and pipelines metal for the purpose of the first generation power units service life extension are presented. The codes and normative documents elaborated by VNIIAES is considered, which determines the procedure and the order of work for assessment of the technical conditions and residual lifetime of power units concerning its thermal and mechanical equipment elements and pipelines. The results of complex metal research of pipelines and equipment of the first generation power units executed by VNIIAES in cooperation with other industry's organizations are submitted. This research has included the application of new inspection methods and metal research methodology, elaborated by VNIIAES and other organizations, which allow to give the forecast for planned operational terms for NPPs outside of 30 years limits. There are also submitted the summary results of work regarding the assessment of the technical conditions and residual lifetime of the inspected technological systems elements of the first generation power units. The results being received made up the base for obtaining the licenses for operation of the first generation power units above the 30 years limits. Work regarding the assessment of the metal of the thermal and mechanical equipment with the purpose of service life extension are proceeding now both in a way of improving the methods and equipment for metal inspection, and in direction of practical application of the research methods being submitted