Long-term operation (LTO) of nuclear power plant (NPP) units are conditional on the compliance with strict safety standards. In order to ensure continuous safe operation of world reactors, it is necessary to solve specific issues that affect renewed licensing for LTO. The objective of LTO licensing program is to demonstrate that the relevant structures, systems and components (SSC) shall perform their safety functions in compliance with all the requirements throughout the entire LTO period.

The study of effects of long-term exposures has particular problems. For evaluation, it is necessary to use material exposed for a long time under operating conditions, or to use accelerated aging procedures, which however, not fully correspond to the real state.
Decommissioning of two V1 units in Slovakia brings a big possibility to obtain materials from equipment that was in conditions of real operation for decades (28 or 29 campaigns).
VUJE, in cooperation with JAVYS Company, is creating a material archive from the main components of the decommissioned V1 NPP units. The unique materials can serve as a base for various experimental tests (structural and substructural analyzes, tests of mechanical properties, fracture-mechanical analyzes, calculations of resistance to unstable fracture propagation, evaluations from NDT inspections , etc.) and achieved results will provide a strong contribution to the qualification processes facing the future LTO - not only for the VVER technology but for the LWR in general. 

The archive includes material samples from steam-generators (SG), pressurizers, primary piping, reactor pressure vessel, nozzles, tubes, concrete and other parts.
Meantime, several projects are being prepared or are already being implemented directly using this material archive, e.g. for evaluation of SG parts, piping parts or internal reactor parts.