VERLIFE - Unified Procedure for Lifetime Assessment of Components and Piping in WWER NPPs During Operation: Updating and Further Development

VERLIFE — “Unified Procedure for Lifetime Assessment of Components and Piping in WWER NPPs during Operation” was developed within the 5th Framework Program of the European Union in 2003 and later upgraded within the 6th Framework Program “COVERS – Safety of WWER NPPs” of the European Union in 2008. This Procedure had to fill the gap in original Soviet/Russian Codes and Rules for WWER type NPPs, as these codes were developed only for design and manufacturing and were not changed since their second edition in 1989. VERLIFE Procedure is based on these Russian codes but incorporates also new developments in research, mainly in fracture mechanics, and also some principal approaches used in PWR codes. To assure that VERLIFE Procedure will remain a living document, new 3-years IAEA project (in close co-operation with the another project 6th Framework Program of the European Union “NULIFE – Plant Life Management of NPPs”) has started in 2009. Within this project, upgrading/updating of the VERLIFE procedure is prepared together with the extension by (at least) following procedures: - Leak-before-break concept for WWER NPPs; - Reduction of Probability of Break procedure for evaluation of integrity of high-energy piping in NPPs of WWER-440 and WWER-1000 types; - Lifetime of reactor pressure vessel internals; - Risk informed In-service inspection implementation process and organization; - Methodology for Qualification of In-Service Inspection Systems for WWER Nuclear Power Plants; - Component and piping supports; - Monitoring and evaluation of erosion-corrosion damage in piping materials. Final document, after its approval by expert groups of the IAEA and NULIFE, will be issued as “IAEA/NULIFE Guidelines for Integrity and Lifetime Assessment of Components and Piping in WWER NPPs”. The paper will describe these main principles and also future plans.