IAEA-NULIFE VERLIFE - Procedure for integrity and lifetime assessment of components and piping in WWER NPPs during operation - Tool for LTO

VERLIFE - 'Unified Procedure for Lifetime Assessment of Components and Piping in WWER NPPs during Operation' was developed within the 5th Framework Programme of the European Union in 2003 and later upgraded within the 6th Framework Programme '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 manufacture 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 cooperation with another project of the 6th Framework Programme of the European Union 'NULIFE - Plant Life Management of NPPs') has started in 2009. Final document, was approved by expert groups of the IAEA and NULIFE in June 28-30, 2011, and will be issued as 'IAEA/NULIFE Guidelines for Integrity and Lifetime Assessment of Components and Piping in WWER NPPs during Operation'. This document represents a necessary part for any integrity and lifetime assessment during operation that is a bases for further decision about safe and potential long term operation. To prepare documents like TLAA, it is necessary to have a tool that is able to evaluate lifetime of the main NPP components taking into account existing past operation as well as proposal for the future. (author)