Plant life extension and ageing mechanisms: an ANSALDO proposal for the application to Kozloduy NPPs

In the frame of extension of NPP's installations lifetime, ageing management has become a topical subject to obtain the items: - Evaluation of residual life of the plant through the investigation of the residual life of well identified Safety Related Equipment in the as built configuration; - Organization of identified representative equipment per typological Classes (as Piping Systems, Tanks, Valves, Pumps, Electrical Equipment, Pressurized Components) in order to define for each High Level Class a set of elementary families capable to have, within each family, a common ageing mechanism and methodological investigation and potential common on-line monitoring; Application of a consistent methodology for residual life evaluation at each High Level Class (and subsequent elementary family and group if any) in order to assess an integral approach to backfitting and ageing management, taking also into account the economical investment effort required to the utility. In this report, a technical proposal for the application of the ANSALDO standard methodology approach, applied to the re-evaluation of the Kozloduy NPP's (Unit 1 - to 4) is presented. (authors)